1. The Basics of Cholesterol

“My doctor says my cholesterol is through the roof. I really have to do something about my cholesterol.”

Naturally, the term “cholesterol” has negative connotations. It’s understandable, given cholesterol’s villainous role in the cardiovascular health story.

But just as every good tale needs a villain, and just as most memorable villains have both good and bad qualities, so the story goes with cholesterol.

The Good

On the good side, your body requires some cholesterol. In fact, the waxy, fat-like material we know as cholesterol is found in each of the trillions of cells that make you who you are. Cholesterol is a key component that helps to stabilize the cell membrane, which protects and organizes each cell.

Indirectly, cholesterol contributes to stronger bones. Skin exposure to the sun’s ultraviolet rays triggers the conversion of a form of cholesterol into vitamin D, which your body uses to absorb bone-building calcium. This important vitamin also may be necessary for muscle and immune function, and researchers are studying its role in cardiovascular health and, potentially, prevention of diabetes and certain cancers.

Furthermore, cholesterol serves as a precursor to bile salts, which help your body to digest fats and fat-soluble vitamins consumed in food. Likewise, steroid hormones—such as the male and female sex hormones (androgens and estrogens) and glucocorticoids (hormones produced by the adrenal gland that control a variety of functions in the body)—are derived from cholesterol.

The Not-So Good

Trouble is, your liver produces all the cholesterol your body needs to carry out these important functions.

By eating foods high in saturated fat and trans fat, you can prompt the liver to produce even more cholesterol, which then circulates in the blood. As cholesterol levels in your bloodstream rise, so does your risk of cardiovascular disease, heart attack, and stroke.

The Lowdown on Lipoproteins

Cholesterol is one of several fatty substances known as lipids that are found in your blood and tissues. As the key regulator of lipid levels in your body, your liver produces about three-quarters of the cholesterol in your body (all cells can make some cholesterol, too) and also helps remove it from the body.

Cholesterol generated in the liver is transported throughout the body on small carrier particles known as lipoproteins, which consist of lipids and proteins:

• Low-density lipoproteins (LDL) carry cholesterol from the liver throughout the bloodstream. LDL cholesterol is often referred to as “bad” cholesterol because high LDL levels result in accumulation of cholesterol in the arteries.
• High-density lipoproteins (HDL) scavenge and transport LDL cholesterol from your body back to your liver, where it’s converted to bile salts and eliminated from the body in feces. For this reason, HDL is often called “good” cholesterol. Higher levels may protect against cardiovascular disease, whereas low levels may increase your risk. Although it’s beneficial, HDL does not remove all LDL cholesterol from the bloodstream—only about a quarter to one-third of it, according to the American Heart Association.

Overall, the right balance of LDL and HDL is critical for good cardiovascular health.

Triglycerides: The Forgotten Fat

Chances are, when you think about lipids and heart health, cholesterol comes to mind. But, you shouldn’t forget about another type of lipid floating in your blood that may increase your cardiovascular risk: triglycerides.

While cholesterol is vital for cell development, vitamin D synthesis, and production of bile salts, triglycerides are the storage centers for the calories (energy) from food that your body doesn’t use right away. When that energy is needed, hormones release triglycerides from your fat cells.

Triglycerides are the most prevalent type of fat in your body. High triglycerides, or hypertriglyceridemia, can occur if you consume more calories than you burn, especially excess calories from carbohydrates. Combined with a low HDL or high LDL level, hypertriglyceridemia is associated with an increased risk of cardiovascular disease.

Like cholesterol, triglycerides cannot dissolve in the blood, so they too are carried throughout the bloodstream on lipoproteins—namely, very low-density lipoproteins, or VLDL.

Elevated VLDL has been linked to cardiovascular disease. However, since VLDL is not easily measured, it may not be included as a separate result in routine cholesterol testing, but rather as a percentage of your triglyceride total.

What Causes Cholesterol Abnormalities?

A number of factors—many preventable, others not—can cause abnormal lipid levels in the blood, or dyslipidemia (hyperlipidemia):

The Factors You Can Control

A Poor Diet

Diets high in saturated fat and trans fat are linked to higher LDL cholesterol levels. Saturated fats are found in animal products, especially fatty red meat (such as beef and pork) or processed meats (e.g., sausage, bacon, salami), as well as full-fat dairy products.

Trans fats, also known as partially hydrogenated oils, are prevalent in many processed foods, among them baked goods, fried foods, and frozen pizzas.

Trans fats cause a double-whammy on cardiovascular health by increasing LDL cholesterol and also reducing beneficial HDL cholesterol. (In 2015, the U.S. Food and Drug Administration [FDA] ordered food manufacturers to remove trans fats from the food supply by 2018.)

Physical Inactivity

A sedentary lifestyle can cause a decline in HDL, which leaves fewer of these LDL scavengers to remove the “bad” cholesterol from your bloodstream and arteries.

Conversely, research suggests that staying (or becoming) physically active can increase HDL levels and also increase the size of LDL particles, making them less deleterious.

Obesity

If you’re overweight or obese, you’re more likely to have higher LDL and triglyceride levels and lower HDL levels. However, losing weight may help restore a better cholesterol balance.

Smoking

Like a sedentary lifestyle, tobacco smoking has been shown to reduce healthful HDL cholesterol. However, research suggests that quitting smoking can help improve your HDL count.

Medical Conditions

Several medical conditions can adversely affect your lipid profile:

• Diabetes: The high blood sugar of diabetes can contribute to elevations in LDL cholesterol and triglycerides and cause declines in HDL cholesterol. This condition is known as diabetic dyslipidemia. Research suggests that prediabetes, or insulin resistance—elevated blood-sugar levels that may foreshadow type 2 diabetes—also is associated with diabetic dyslipidemia and cardiovascular disease. So, preventing type 2 diabetes by maintaining a healthy weight and adhering to a healthy diet and exercise regimen can have positive effects on your cholesterol.
• Thyroid dysfunction: The thyroid is important for cholesterol regulation. Hypothyroidism, or underactive thyroid, can cause increases in triglycerides, LDL, and total cholesterol. Some studies suggest that even a mild, asymptomatic form of the disease, known as subclinical hypothyroidism, may cause these elevations, but to a lesser extent. Correcting an underactive thyroid may help improve your lipid levels. So, if you have high cholesterol, ask your doctor whether your thyroid could be to blame and whether you should be tested for thyroid dysfunction.
• Kidney disease: Elevated lipid levels often accompany chronic kidney disease, and research suggests that high cholesterol and triglycerides may be risk factors for kidney disease progression.
• Polycystic ovary syndrome: Women with this condition, caused by an imbalance of reproductive hormones, may have high LDL and low HDL levels, and are at increased risk of atherosclerosis.
• Pregnancy: Lipid alterations, such as increases in triglycerides and total cholesterol, can occur during pregnancy.

Medications

A number of prescription medications used for an array of medical conditions can affect cholesterol levels to varying degrees. Some examples of these medications include the following:

• Blood pressure medicines: Thiazide diuretics, such as hydrochlorothiazide, may increase cholesterol and triglyceride levels. Older beta blocker medications, such as atenolol (Tenormin®) and metoprolol (Lopressor®, Toprol®) can cause slight increases in triglycerides and slight reductions in HDL cholesterol.
• Amiodarone: This drug, marketed as Cordarone® and Pacerone®, is used to treat irregular heart rhythms. The medication may increase cholesterol and triglyceride levels.
• Antipsychotic drugs: Several first- and second-generation medications used to treat schizophrenia and other psychotic conditions can increase total cholesterol and triglycerides. Examples of first-generation antipsychotics include chlorpromazine (Thorazine®), haloperidol (Haldol), and loxapine (Loxitane®), while the list of second-generation antipsychotics includes aripiprazole (Abilify®), olanzapine (Zyprexa®), and risperidone (Risperdal®), among others.
• Corticosteroids: These potent anti-inflammatory and immunosuppressive drugs used to treat rheumatic conditions such as rheumatoid arthritis, lupus, and other disorders, may cause increases in LDL cholesterol and triglycerides. Members of this drug class include dexamethasone, prednisone, and prednisolone, among others.
• Oral contraceptives: Use of some birth control pills may result in increased total cholesterol and triglycerides.
• Antidepressants: Certain medications used to treat depression, such as desvenlafaxine (Pristiq®) and venlafaxine (Effexor®), may increase LDL cholesterol and triglycerides.

Use of these medications may affect your lipid profile, but the extent to which it influences your cardiovascular risk remains unclear. Also, keep in mind that, in many cases, the benefits of these medications outweigh any potential risks posed by their lipid-altering effects. So, talk to your physician about your individual risk/benefit profile.

The Factors Beyond Your Control

Age

Your cholesterol tends to rise as you get older, making advancing age a risk factor for high cholesterol.

Gender

Until the age of menopause, women typically have lower LDL and total cholesterol levels than men do; however, with menopause, LDL cholesterol and triglycerides tend to increase, while HDL levels often decline or stay the same. LDL levels rise more quickly for women than for men, according to the Centers for Disease Control and Prevention (CDC). But, overall, men at any age usually have lower HDL levels compared to women, the CDC notes.

Race

The American Heart Association’s 2015 heart disease and stroke statistics (Circulation, Jan. 27, 2015) suggest some variations in cholesterol levels among different races. For instance, among men age 20 and older, the prevalence of high LDL cholesterol (130 mg/dl or higher) was 38.8 percent among Hispanic men, compared with 29.4 percent among non-Hispanic white men and 30.7 percent of non-Hispanic black men.

Among women, high LDL was most prevalent among non-Hispanic black women (33.6 percent), compared with non-Hispanic white women (32 percent) and Hispanic women (31.8 percent).

The statistics also show that rates of low HDL cholesterol (below 40 mg/dl) were highest among Hispanic men (33.8 percent) versus non-Hispanic white men (28.7 percent) and non-Hispanic black men (20 percent).

For women, the prevalence of low HDL was greatest in Hispanic women (12.8 percent), compared with 10.3 percent of non-Hispanic black women and 10.2 percent of non-Hispanic white women.

Family History

Genetics plays a role in how much cholesterol your body produces. People with a family history of high cholesterol may be more likely to have high cholesterol themselves and may need to have their cholesterol checked more frequently, according to the CDC.

About 1.5 million Americans have a genetic condition known as familial hypercholesterolemia, which causes very high LDL cholesterol levels at a young age. (See Chapter 3 for more about genetics, cholesterol, and cardiovascular risks.)

Know What to Do

Now that you’ve learned the basics about cholesterol, the factors that adversely affect your cholesterol levels, and the importance of managing your cholesterol, what do you do with that information?

The answer is simple: You have to put it in the context of cardiovascular disease and understand how to reduce your LDL cholesterol and your overall risk.

Yet, if you’re like many Americans, you’re unclear about the right path to take to bring your cholesterol under control, suggests a 2017 survey from the American Heart Association (AHA).

The AHA surveyed more than 800 people across the U.S. who either had a history of cardiovascular disease or at least one major risk factor for heart disease, such as high LDL levels, high blood pressure, or diabetes. Most of those surveyed said they knew that managing their cholesterol was important, but they also reported being unsure about how to do it and said they were not confident their cholesterol could be controlled. Additionally, nearly half of the survey respondents who had at least one major heart disease risk factor reported that they had not had their cholesterol levels checked within the past year.

“We wanted to get a sense of what people know about their cholesterol risk and its connection to heart disease and stroke, as well as how people engage with their healthcare providers to manage their risks,” Mary Ann Bauman, MD, a member of the AHA’s cholesterol advisory group, said in a statement. “We found even among those people at the highest risk for heart disease and stroke, overall knowledge was lacking and there was a major disconnect between perceptions about cholesterol and the significance of its health impact.”

In general, the survey found that people with a history of heart disease or with heart disease risk factors had lower perceptions of their real health risks. Only about 29 percent of survey participants who had heart disease knew that they were at an elevated risk for a second heart attack or other cardiovascular event, such as a stroke.

“Research suggests even modestly elevated cholesterol levels can lead to heart disease later in life, but these survey results show an alarming lack of communication between healthcare providers and those most at risk for cardiovascular disease,” Dr. Bauman added. “Current guidelines call for lifestyle modifications as a first-line treatment, but that’s often not enough. We also need to talk to patients about other risk factors, including genetics and family history, to determine the most effective course of treatment for each individual.”

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